1. Field of the Invention (Technical Field)
The present invention relates to fractional destructive distillation, particularly to fractional destructive distillation arrays, and more specifically to a pyrolytic distillation apparatus that is self-compensating for differential thermal expansion.
2. Description of Related Art
Destructive distillation of organic containing materials, also known as pyrolysis, has been known for some time. Such systems are particularly useful for treating, recovering, and recycling waste products and waste constituents. Discarded materials containing appreciable quantities of hydrocarbons are particularly attractive candidates for pyrolytic distillation and recovery. Motor vehicle tires, for instance, contain large amounts of potentially useful carbon and hydrocarbons compositions which, if recovered, are desirable for re-use. Discarded tires alone account for nearly two percent of all solid waste. Further, discarded tires pose health and environmental challenges due in part to their extremely slow deterioration rate, flammability, and potentially hazardous gasses emitted when ignited.
Several systems have been created in an attempt to successfully recycle organic materials. Destructive distillation systems currently in use typically heat the organic containing materials in a large airtight chamber at a very high temperature. Heating organic materials to high temperatures, ordinarily while also minimizing the amount of available air (oxygen), results in the pyrolysis of the material into simpler (usually more useful) constituent compounds. Thus owing to the lack of available oxygen in the airtight pyrolysis chamber, the organics-containing materials disposed therein break down into their ingredient chemical substances.
Many or most pyrolytic distillation systems currently in use are “batch” processors, whereby a defined quantity of feedstock is introduced into the treatment chamber, the chamber is closed while the material undergoes pyrolysis, and the chamber is opened to remove the resulting by-products and to introduce a new batch of feedstock to repeat the process. A drawback to such an airtight chamber design is that the chamber must be periodically opened and the residue which builds up therein must be cleaned out. Serial treatment of separate batches of material is inefficient relative to “continuous” processing.
Known systems and methods for pyrolysis of wastes, including used motor vehicle tires, include the disclosures of the following United States patents, to which reference is made for background on the science of pyrolytic and fractional distillation of solid wastes: U.S. Pat. No. 6,835,861 to Nichols, et al.; U.S. Pat. No. 6,736,940 to Masemore, et al.; U.S. Pat. No. 6,372,948 to Flanigan; U.S. Pat. No. 6,271,427 to Ershag; U.S. Pat. No. 6,221,329 to Faulkner, et al.; U.S. Pat. No. 5,167,772 to Parker, Sr.; and U.S. Pat. No. 4,740,270 to Roy.
Auger elements contained within a stack or array of sealed conduits can be used to construct a continuous flow distillation system. In such systems, an array of conveyors moves feedstock through the closed conduits (such as pipes or tubing). Continuous flow distillation systems permit processing on an ongoing basis, improving system efficiency by reducing significantly the need to access the interior of the otherwise airtight pyrolysis chamber.
However, due to the extreme difference in temperature encountered throughout a continuous system, differential thermal expansion causes great difficulties to creating a successfully operating design. There is thus a present need for a method and apparatus which provides a successfully operating continuous flow fractional destructive distillation array which can self-adjust for large amounts of differential thermal expansion.